This invention relates to an electronic device, in the nature of a hand held calculator, for displaying in sequence intervals of chords for various keys for a fretted stringed instrument. More particularly, the invention relates to an electronic device which uses a logic system for storing, and then displaying as selected, the finger positions for the strings of a fretted stringed instrument represented by a selected chord or selected series of musical intervals in a selected key. Variations of the device permit sequential displaying of alternative finger positions for a particular chord, sequential display of different types of chords (e.g. major, minor, diminished, augmented, etc.) once a particular key has been selected, and sequential display of a particular type of chord in different keys.
Of background interest is my co-pending U.S. application Ser. No. 871,173 filed Jan. 23rd, 1978 for "Electronic Display Device for Fretted Stringed Instruments". That application relates to an electro-mechanical system for displaying in a display area the finger positions for the strings of a fretted stringed instrument represented by a selected key and a selected series of musical intervals. What appears in the string and fret display is predetermined by the co-selection of related key and musical interval switches and does not require the use of any logic system other than in an associated numeric display used to identify the bar position fret for a selected chord. That device does not provide for chords having "open" strings, i.e. chords in which not all of the strings of the instrument are played, and is limited in the number of chords which can be displayed, since essentially a separate circuitry must be provided for each desired chord in each desired key.
Other references of background interest describing and illustrating display devices for stringed musical instruments having some electronic features include Johnson, Jr., et al U.S. Pat. No. 3,978,757 issued Sept. 7th, 1976, Weitzner U.S. Pat. No. 3,403,591 issued Oct. 1st, 1968 and Weitzner U.S. Pat. No. 3,379,087 issued Apr. 23rd, 1968.